Where is the sound coming from?
When the lid is open, the many strings of this fortepiano are visible. The longer the string, the lower the pitch. To produce sound, the strings must be plucked, bowed, or, in this case, struck.
The mechanics of the string strike are hidden in the concealed areas behind the keys.
Fortepiano (1814) by Nannette StreicherLandesmuseum Württemberg
On the trail of sound
Several rows of tuning pins are located between the wooden covers. The strings are attached here and can be tuned to the correct pitch by turning the pins.
How exactly the strings are struck remains hidden from view.
Piano action model based on Johann Andreas Stein 1773 (Last third of the 19th Century) by Carl Anton PfeifferLandesmuseum Württemberg
Visualization and Learning Model
More than 250 piano action models from the musical instrument collection of the Landesmuseum Württemberg allow a closer look at the hidden sound production process. When the key is pressed, a small hammer with a piece of felt strikes the string from below. The hammer gains the right momentum by its rear end being caught in the hopper, catapulting the front end with the hammer head against the string.
A glance behind the keys
What actually happens when a key is pressed? Inside the instrument, a mechanism is set in motion. The video reveals what is otherwise hidden—the process from the moment the key is pressed to the moment the sound is produced.
Piano action model based on Bartolomeo Cristofori 1725 (Last third of the 19th Century) by Carl Anton PfeifferLandesmuseum Württemberg
A piano is a piano, right?
With so many action models, one thing becomes clear: not every keyboard instrument works the same way. One early model follows Bartolomeo Cristofori’s (1655-1731) design. In the late 17th century, he replaced the harpsichord’s plucking action with hammers striking the strings, allowing players to vary the volume.
About Bartolomeo Cristofori
Bartolomeo Cristofori made efforts to enable variations in volume on the keyboard instrument. He is often regarded as the ‘inventor’ of the hammer piano. Note the piano keyboard beneath his left hand: the unknown portrait artist was presumably less concerned with piano construction and simply left out the black keys.
Progress, improvement, sound quality
120 years later, Sébastien Érard's (1752–1831) complex innovations form the basis for the concert grand pianos used today. The technical improvements were designed to allow the keys to be struck in quick succession, reduce wear and tear on the mechanics, and prevent squeaking noises affecting the sound.
Fortepiano (1784) by Johann Andreas SteinLandesmuseum Württemberg
Mozart favours, Beethoven demands
Wolfgang Amadeus Mozart (1756–1791) had strong opinions about how a good piano should sound and feel to play. Although he appreciated instruments from the workshop of Franz Jakob Späth (1714–1786), he was particularly impressed by a pianoforte made by Johann Andreas Stein (1728–1792) in 1777.
Fortepiano (1784) by Johann Andreas SteinLandesmuseum Württemberg
He wrote enthusiastically to his father about the instrument’s precise touch and the direct transmission from the key to the hammer: “Before I had even seen Stein’s work, I preferred the Spät-style pianos; but now I must give preference to Stein’s.” The reason for this was a technical innovation: Stein’s "German action", which Mozart had encountered in Augsburg.
Viennese or english action?
Ludwig van Beethoven (1770–1827) was closely associated with J. A. Stein's daughter and company heiress Nannette Streicher (1769–1833, b. Stein) in Vienna. In pursuit of his ideal sound, Beethoven repeatedly asked her for new instruments and improvements. He also tried out innovative English fortepianos, in which the hammer is struck rather than bounced with a hopper. The descendants of the English hammer mechanism are now used internationally.
Front view of the Landesgewerbemuseum in Stuttgart (1896) by Peter Schnorr (Drawing), Hofkunstanstalt Martin Rommel & Co (Print)Landesmuseum Württemberg
Built and collected
The Stuttgart piano manufacturer Carl Anton Pfeiffer (1861–1927) added to his collection of historical keyboard instruments with many piano action models, some of which he made himself. He donated his collection to the Landesgewerbemuseum at the beginning of the 20th century.
The various action models formed a study collection that provided a vivid illustration of the technical development of keyboard instruments. In 1968, the Landesmuseum Württemberg took over this extensive collection.
Pfeiffer's piano action models
Among Pfeiffer's large collection of piano action models, there are a few whose mechanisms correspond exactly to a historical musical instrument in the keyboard instrument collection.
Square Piano (1770) by Johann Matthäus SchmahlLandesmuseum Württemberg
This includes the “C45” action model. It is a perfect match for the action of the harp-shaped table piano built by Johann Matthäus Schmahl (1734–1793). The Ulm-based instrument maker belonged to a well-known family of organ and instrument builders and, in addition to organs, also made various keyboard instruments.
Piano action model based on Johann Matthäus Schmahl 1770 (Last third of the 19th Century) by Carl Anton PfeifferLandesmuseum Württemberg
Mechanical replica
Pfeiffer was able to base the construction of this mechanism directly on the instrument itself. Other models of mechanisms, such as Cristofori's, were reconstructed by him on the basis of drawings and descriptions.
Schmahl's english action
This model has a square piano action. The strings do not run straight back behind the key, but to the side. The hammer points forwards, and the jack of the english action is a small wooden stick that sits loosely on the rear end of the key. A two-armed lever activates the damping mechanism to dampen the resonating string – but it can also be switched off.
action replicas
Customized sound
A central lever and four sliders above the keyboard allow the sound to be altered. The lever controls the damping mechanism, while the sliders offer different effects: leather (“pianissimo”) or silk (“piano”) strips soften the sound, wool fringes dampen the strings, and raising the soundboard produces a thinner tone.
Grand piano model (1897) by Otto PfeifferLandesmuseum Württemberg
From a historical instrument to a concert grand piano
Most modern concert grand pianos are based on action principles that evolved from the historical jack action. Action models illustrate this evolution: they demonstrate how different types of action work and how they have changed over time. In this way, they offer a glimpse into the hidden inner workings of the instruments — without having to take the valuable originals apart.
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Experience Local Musical History in Person
Curious? Then come experience these historical keyboard instruments for yourself! At the "House of Music" at the Landesmuseum Württemberg, you can explore the instruments up close and learn more about their history, both in terms of sound and technology. We look forward to your visit!
Landesmuseum Württemberg, Stuttgart
Concept and Project Management: Charlotte Schönebeck, M.A.
Editing and Implementation: Hanna Warth-Geraci
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